Parental self-feeding effects on parental care levels and time allocation in Palestine sunbirds.

Markman S - PLoS ONE (2014)

Bottom Line:
Until now the effect of food consumption by parent birds on their food delivery to their young as well as other parental activities has rarely been studied.Nestling food intake and growth rate increased with increasing food quality of parents and decreasing brood size.These results imply that increasing the nutrient content of foods consumed by parent sunbirds allow them to increase the rate at which other foods are delivered to their young and to increase the time spent on other parental care activities.

Affiliation: Department of Biology and Environment, University of Haifa - Oranim, Tivon, Israel.

ABSTRACTThe trade-off between parents feeding themselves and their young is an important life history problem that can be considered in terms of optimal behavioral strategies. Recent studies on birds have tested how parents allocate the food between themselves and their young. Until now the effect of food consumption by parent birds on their food delivery to their young as well as other parental activities has rarely been studied. I have previously shown that parent Palestine sunbirds (Nectarinia osea) will consume nectar and liquidized arthropods from artificial feeders. However, they will only feed their young with whole arthropods. This provided a unique opportunity to experimentally manipulate the food eaten by parents independent of that fed to their offspring. Here, I hypothesized that parents invest in their current young according to the quality of food that they themselves consume. Breeding pairs with two or three nestlings were provided with feeders containing water (control), sucrose solution (0.75 mol) or liquidized mealworms mixed with sucrose solution (0.75 mol). As food quality in feeders increased (from water up to liquidized mealworms mixed with sucrose solution): 1) Parents (especially females) increased their food delivery of whole arthropod prey to their young. 2) Only males increased their nest guarding effort. Nestling food intake and growth rate increased with increasing food quality of parents and decreasing brood size. These results imply that increasing the nutrient content of foods consumed by parent sunbirds allow them to increase the rate at which other foods are delivered to their young and to increase the time spent on other parental care activities.

pone-0113890-g002: Time spent at the nest per parental visit (means ± SE) by Palestine sunbirds plotted against brood size (2 or 3 nestlings), quality of food available in an artificial feeder, which was either water (Water), sucrose solution (Sugar) or sucrose and mealworm solution (Sugar and Worms), and parental sex (blank: males; cross hatched: females).The values consist of the average for the whole seven days of the manipulation period (from nestlings being 7 days of age until 13 days of age) for each parent.

Mentions:
Females spent significantly more time at the nest than males (Table 2b, Fig. 2). Although the type of food in a feeder did not have a significant effect on the time spent at the nest (Table 2b, Fig. 2), there was a tendency of the females to spend more time at a nest with more food types in the feeder, with the opposite response in males. This resulted in a significant parental sex by food treatment interaction term (Table 2b).

pone-0113890-g002: Time spent at the nest per parental visit (means ± SE) by Palestine sunbirds plotted against brood size (2 or 3 nestlings), quality of food available in an artificial feeder, which was either water (Water), sucrose solution (Sugar) or sucrose and mealworm solution (Sugar and Worms), and parental sex (blank: males; cross hatched: females).The values consist of the average for the whole seven days of the manipulation period (from nestlings being 7 days of age until 13 days of age) for each parent.

Mentions:
Females spent significantly more time at the nest than males (Table 2b, Fig. 2). Although the type of food in a feeder did not have a significant effect on the time spent at the nest (Table 2b, Fig. 2), there was a tendency of the females to spend more time at a nest with more food types in the feeder, with the opposite response in males. This resulted in a significant parental sex by food treatment interaction term (Table 2b).

Bottom Line:
Until now the effect of food consumption by parent birds on their food delivery to their young as well as other parental activities has rarely been studied.Nestling food intake and growth rate increased with increasing food quality of parents and decreasing brood size.These results imply that increasing the nutrient content of foods consumed by parent sunbirds allow them to increase the rate at which other foods are delivered to their young and to increase the time spent on other parental care activities.

Affiliation:
Department of Biology and Environment, University of Haifa - Oranim, Tivon, Israel.

ABSTRACTThe trade-off between parents feeding themselves and their young is an important life history problem that can be considered in terms of optimal behavioral strategies. Recent studies on birds have tested how parents allocate the food between themselves and their young. Until now the effect of food consumption by parent birds on their food delivery to their young as well as other parental activities has rarely been studied. I have previously shown that parent Palestine sunbirds (Nectarinia osea) will consume nectar and liquidized arthropods from artificial feeders. However, they will only feed their young with whole arthropods. This provided a unique opportunity to experimentally manipulate the food eaten by parents independent of that fed to their offspring. Here, I hypothesized that parents invest in their current young according to the quality of food that they themselves consume. Breeding pairs with two or three nestlings were provided with feeders containing water (control), sucrose solution (0.75 mol) or liquidized mealworms mixed with sucrose solution (0.75 mol). As food quality in feeders increased (from water up to liquidized mealworms mixed with sucrose solution): 1) Parents (especially females) increased their food delivery of whole arthropod prey to their young. 2) Only males increased their nest guarding effort. Nestling food intake and growth rate increased with increasing food quality of parents and decreasing brood size. These results imply that increasing the nutrient content of foods consumed by parent sunbirds allow them to increase the rate at which other foods are delivered to their young and to increase the time spent on other parental care activities.